SiC SUBSTRATE EVALUATION METHOD AND METHOD FOR MANUFACTURING SiC EPITAXIAL WAFER

ABSTRACT

In a SiC substrate evaluation method, a bar-shaped stacking fault is observed by irradiating a surface of a SiC substrate before stacking an epitaxial layer with excitation light and extracting light having a wavelength range from equal to or greater than 405 nm and equal to or less than 445 nm among photoluminescence light beams emitted from the first surface.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a SiC substrate evaluation method and amethod for manufacturing a SiC epitaxial wafer.

Priority is claimed on Japanese Patent Application No. 2018-194020,filed on Oct. 15, 2018, the content of which is incorporated herein byreference.

Description of Related Art

Silicon carbide (SiC) has a dielectric breakdown electric field oneorder of magnitude larger and a band gap three times larger than silicon(Si). In addition, silicon carbide (SiC) has a characteristic such as athermal conductivity being approximately three times higher than silicon(Si). Silicon carbide (SiC) is expected to be applied to power devices,high frequency devices, high temperature operation devices and the like.

Devices such as semiconductors using SiC (hereinafter referred to as SiCdevices) are formed on SiC epitaxial wafers in which epitaxial layersare formed on SiC substrates. Hereinafter, a wafer before forming anepitaxial layer will be referred to as a SiC substrate, and a waferafter forming an epitaxial layer will be referred to as a SiC epitaxialwafer.

A SiC substrate is obtained by slicing a SiC ingot. A SiC epitaxialwafer includes a SiC substrate and an epitaxial layer. The epitaxiallayer is stacked on one surface of the SiC substrate by chemical vapordeposition (CVD) or the like. The epitaxial layer becomes an activeregion of a SiC device.

Si substrates widely used in semiconductor devices can be manufacturedwith high quality and do not require epitaxial layers. On the otherhand, SiC substrates have a larger number of defects than the Sisubstrates. The epitaxial layer is formed to improve the quality of aSiC device.

Japanese Unexamined Patent Application, First Publication No. 2016-25241discloses that the surface of a SiC epitaxial wafer after forming anepitaxial layer is evaluated by a photoluminescence method.

SUMMARY OF THE INVENTION

SiC devices may have degraded characteristics (bipolar degradation mayoccur) when a voltage is applied in a forward direction. A singleShockley-type stacking fault is said to be one of the causes of thebipolar degradation. The single Shockley-type stacking fault is formeddue to expansion of a basal plane dislocation when a voltage is appliedin a forward direction of a SiC device including the basal planedislocation in an active region. There is a concern that this bipolardegradation may not be found in the initial characterization and may beleaked. For this reason, bipolar degradation is a major problem to besolved.

Both a chemical etching method and a photoluminescence method arerepresentative methods for identifying a defect causative of bipolardegradation. In the chemical etching method, the surface of a SiCcrystal is chemically etched with alkali. The chemical etching method isa destructive inspection, and a used substrate cannot be used for themanufacture of a device.

The photoluminescence method is a method of irradiating the surface of asubstrate with excitation light and observing obtained photoluminescencelight. The photoluminescence method is a non-destructive method, and aused substrate can be used for the manufacture of a device.

On the other hand, it is said that the photoluminescence method isuseful to evaluate a SiC epitaxial wafer after stacking an epitaxiallayer, but is difficult to evaluate a SiC substrate before stacking anepitaxial layer. This is because the SiC substrate has a large number ofimpurity levels as compared with the epitaxial layer. An impurityconcentration of the epitaxial layer is, for example, approximately1×10¹⁵ atom/cm³ to approximately 1×10¹⁶ atom/cm³, while an impurityconcentration of the SiC substrate is, for example, approximately 1×10¹⁸atom/cm³. When the impurity concentration is high, the obtainedphotoluminescence spectrum become broad, and it becomes difficult toidentify a specific defect.

Among the defects that cause bipolar degradation, there are defects inwhich the defects of the SiC substrate are taken over by the epitaxiallayer. If defects can be specified at the time of the SiC substrate, theproduction yield of high-quality SiC epitaxial wafers can be increased.There is a need for a method capable of non-destructively distinguishingspecific defects.

The present invention is contrived in view of the above-describedproblem, and an object thereof is to provide a SiC substrate evaluationmethod for identifying a bar-shaped stacking fault at the time of SiCsubstrate before stacking an epitaxial layer thereon.

A basal plane dislocation and the like are known as defects causative ofbipolar degradation. Basal plane dislocations are decreasing with theprogress of crystal growth techniques. With the decrease in basal planedislocations, investigations have been made to identify and suppressother defects. Based on such investigations, the inventor has givenattention to a bar-shaped stacking fault as a new defect and has found amethod for identifying a bar-shaped stacking fault at the time of a SiCsubstrate, that is, at the time of a SiC substrate before stacking anepitaxial layer thereon.

That is, the present invention provides the following means in order tosolve the above-described problem.

A SiC substrate evaluation method according to a first aspect includesobserving a bar-shaped stacking fault by irradiating a first surface ofa SiC substrate before stacking an epitaxial layer with excitation lightand extracting light having a wavelength range of equal to or greaterthan 405 nm and equal to or less than 445 nm among photoluminescencelight beams emitted from the first surface, wherein the first surface ofthe SiC substrate has an offset angle from a {0001} plane, anirradiation time of the excitation light is equal to or greater than 1msec and equal to or less than 10 sec, and an intensity of theexcitation light is equal to or less than 1 W/cm², and wherein thebar-shaped stacking fault extends in a bar shape in a directionsubstantially perpendicular to the offset direction, the bar-shapedstacking fault has a length in a direction substantially perpendicularto the offset direction with respect to a width in the offset directionis long and the bar-shaped stacking fault has an aspect ratio(length/width) is equal to or greater than 2, and wherein the offsetdirection is the direction of a vector obtained by projecting a normalvector of a {0001} plane onto the first surface of the SiC substrate.

In the SiC substrate evaluation method according to the aspect, awavelength of the excitation light may be equal to or greater than 200nm and equal to or less than 390 nm.

In the SiC substrate evaluation method according to the aspect, thebar-shaped stacking fault may be a single Shockley-type stacking faultextending in a bar shape in a direction substantially perpendicular toan offset direction.

A method for manufacturing a SiC substrate according to a second aspectincludes an evaluation step of evaluating the first surface of the SiCsubstrate using the SiC substrate evaluation method according to theaspect; a determination step of determining whether to stack anepitaxial layer on the basis of results of the evaluation step; and astacking step of stacking an epitaxial layer on the first surface on thebasis of results of the determination step.

A SiC substrate evaluation method according to a third aspect includesobserving a bar-shaped stacking fault by irradiating a first surface ofa SiC substrate before stacking an epitaxial layer with excitation lightand extracting light having a wavelength range of equal to or greaterthan 405 nm and equal to or less than 445 nm in photoluminescence lightbeams emitted from the first surface.

The SiC substrate evaluation method according to the aspect preferablyincludes the following features. It is also preferable to combine one ormore of the following features.

In the SiC substrate evaluation method according to the aspect, awavelength of the excitation light may be equal to or greater than 200nm and equal to or less than 390 nm.

In the SiC substrate evaluation method according to the aspect, thebar-shaped stacking fault may be a single Shockley-type stacking faultextending in a bar shape in a direction substantially perpendicular toan offset direction.

In the SiC substrate evaluation method according to the aspect, anirradiation time of the excitation light may be equal to or greater than1 msec and equal to or less than 10 sec.

In the SiC substrate evaluation method according to the aspect, anintensity of the excitation light may be equal to or less than 1 W/cm².

A method for manufacturing a SiC substrate according to a fourth aspectincludes an evaluation step of evaluating a first surface of the SiCsubstrate using the SiC substrate evaluation method according to theabove-described aspect, a determination step of determining whether tostack an epitaxial layer on the basis of results of the evaluation step,and a growing step of growing an epitaxial layer on the first surface onthe basis of results of the determination step.

A SiC epitaxial wafer according to a fifth aspect includes a SiCsubstrate and an epitaxial layer stacked on a first surface of the SiCsubstrate, in which an area occupied by bar-shaped stacking faults inthe epitaxial layer is equal to or less than ¼ of an area of theepitaxial layer.

In the SiC epitaxial wafer according to the aspect, a density of thebar-shaped stacking faults may be equal to or less than 10 pieces/cm².

According to the SiC substrate evaluation method of the above-describedaspects, it is possible to identify a bar-shaped stacking fault at thetime of a SiC substrate before stacking an epitaxial layer thereon. Inaddition, it is possible to manufacture a SiC epitaxial wafer having asmall number of bar-shaped stacking faults by using the SiC substrateevaluation method.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing comparison between a photoluminescencespectrum of a SiC substrate before stacking an epitaxial layer and aphotoluminescence spectrum of a SiC epitaxial wafer after stacking theepitaxial layer.

FIGS. 2A and 2B are photoluminescence images of a first surface of a SiCsubstrate, FIG. 2A showing a case where a bar-shaped stacking faultlooks white with respect to a normal crystal portion having no defects,and FIG. 2B showing a case where a bar-shaped stacking fault looks blackwith respect to a normal crystal portion having no defects under thesame measurement conditions as in FIG. 2A.

FIG. 3 is an observation diagram of a photoluminescence image of thesurface of a SiC epitaxial wafer after stacking an epitaxial layer on aSiC substrate.

FIGS. 4A and 4B are photoluminescence images of a first surface of a SiCsubstrate, FIG. 4A showing measurement results obtained at the sameposition as in FIG. 2A in a case where a wavelength to be observed isnear-infrared light, and FIG. 4B showing measurement results obtained atthe same position as in FIG. 2B in a case where a wavelength to beobserved is light having a wavelength range in the vicinity of 425 nm.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, preferred examples of the present embodiment will bedescribed in detail with reference to the accompanying drawings asappropriate. In some cases, in the drawings used in the followingdescription, characteristic portions are illustrated at an enlargedscale for convenience of easy understanding of characteristics, and thedimensional ratios and the like of the respective components are notnecessarily the same as the actual ones. In the following description,materials, dimensions, and the like are merely exemplary, do not limitthe present invention, and can be appropriately modified within a rangein which the effects of the present invention are exhibited. Thenumbers, sizes, positions, materials, ratios, shapes and the like may bechanged, added to or omitted as necessary as long as there are noparticular limitations.

“Method for Manufacturing SiC Substrate”

A method for manufacturing a SiC substrate according to the presentembodiment includes a SiC ingot manufacturing step, a SiC substratemanufacturing step, a SiC substrate evaluation step, a SiC substratedetermination step, and an epitaxial layer growing step.

A SiC ingot is a bulk single crystal of SiC. The SiC ingot can bemanufactured by a sublimation recrystallization method or the like.

A SiC substrate is manufactured from the manufactured SiC ingot. The SiCsubstrate is obtained by slicing the SiC ingot. It is preferable thatthe surface of the SiC substrate be ground.

Subsequently, a first surface of the SiC substrate is evaluated. Thefirst surface is a surface on which an epitaxial layer will be grown ina step to be described later. The first surface is evaluated by aphotoluminescence method.

The photoluminescence method is a method of irradiating a material withexcitation light and measuring light emitted when excited electronsreturn to a ground state. The first surface of the SiC substrate isirradiated with excitation light having an energy larger than that of aband gap of SiC, and the intensity of photoluminescence emitted from theSiC substrate is measured. A defect of the SiC substrate, a locationwhere impurities aggregate, and the like are identified by applying aphotoluminescence method to the SiC substrate.

FIG. 1 is a graph showing comparison between a photoluminescencespectrum of a SiC substrate before stacking an epitaxial layer and aphotoluminescence spectrum of a SiC epitaxial wafer after stacking theepitaxial layer. In the graph, both the photoluminescence spectrums havea light emission peak in the vicinity of 390 nm. This light emissionpeak is derived from band edge emission of 4H—SiC. In the SiC epitaxialwafer, a light emission intensity of a light emission peak in thevicinity of 390 nm is significantly larger than light emissionintensities in the other wavelength ranges. In the SiC substrate, lightemission intensities in the other wavelength ranges are also larger thana light emission intensity of a light emission peak in the vicinity of390 nm. This is because the SiC substrate has a larger number ofimpurity levels than the epitaxial layer.

In the photoluminescence method, defects are distinguished from eachother using a difference in a light emission intensity ofphotoluminescence light which occurs due to a difference between a bandgap of a normal crystal portion having no defects and a pseudo band gaphaving a defect due to the structure of the defect. It becomes moredifficult to distinguish between defects as a photoluminescence spectrumbecomes broader.

FIGS. 2A and 2B are photoluminescence images of the first surface of theSiC substrate. FIGS. 2A and 2B are images obtained by irradiating thefirst surface of the SiC substrate with excitation light using a bandpass filter passing a wavelength of 313 nm and measuring aphotoluminescence image of a bar-shaped stacking fault using a high passfilter passing a near-infrared wavelength (a wavelength of 660 nm ormore). FIG. 2A and FIG. 2B are images obtained by measurements performedunder the same conditions.

In FIG. 2A, a bar-shaped stacking fault looks white with respect to anormal crystal portion having no defects. On the other hand, in FIG. 2B,a bar-shaped stacking fault looks black with respect to a normal crystalportion having no defects. That is, appearances of the bar-shapedstacking faults are different from each other regardless of measurementsperformed under the same conditions. In addition, a difference incontrast between the bar-shaped stacking fault and the normal crystalportion having no defects is small, and the bar-shaped stacking fault isobserved blurrily, which results in a difficulty in identification.Therefore, there is a concern that the bar-shaped stacking fault may bemissed and erroneously classified as a basal plane dislocation.

Here, a bar-shaped stacking fault will be described. FIG. 3 is aphotoluminescence image of the surface of a SiC epitaxial wafer afterstacking an epitaxial layer on a SiC substrate. FIG. 3 is an imageobtained by irradiating the surface of the SiC epitaxial wafer withexcitation light using a band pass filter passing a wavelength of 313 nmand measuring a photoluminescence image of a bar-shaped stacking faultusing a high pass filter passing a near-infrared wavelength (awavelength of 660 nm or more).

The bar-shaped stacking fault is a single Shockley-type stacking faultformed in a bar shape. The single Shockley-type stacking fault is causedby a deviation of the arrangement of atoms by one atom. The bar-shapedstacking fault extends in a bar shape in a direction substantiallyperpendicular to an offset direction. In the bar-shaped stacking fault,a length in a direction substantially perpendicular to an offsetdirection with respect to a width in the offset direction is long and anaspect ratio (length/width) is equal to or greater than 2. Since thisbar-shaped—like single Shockley-type stacking fault is the same type asa partial dislocation of a basal plane dislocation, it is expected thatthe stacking fault will expand and bipolar degradation will occur when acurrent is applied to a bipolar device including the defect in a forwarddirection for a long period of time. A stacking fault due to a crystalpolymorphism such as 6H does not expand, and thus the stacking fault canbe found in the initial characterization and excluded.

The offset direction is the direction of a vector obtained by projectinga normal vector of a {0001} plane onto a first surface (crystal growthsurface) of a SiC substrate. The offset direction in FIG. 3 is acrosswise direction in which a left side is an offset upstream side anda right side is an offset downstream side. “Offset upstream” refers to adirection in which the tip of the vector obtained by projecting thenormal vector of the {0001} plane onto the first surface (crystal growthplane) of the SiC substrate is directed, and “offset downstream” is adirection opposite to the offset upstream. In other words, “offsetupstream” refers to an upstream side (starting point side) of step flowgrowth in the SiC substrate, and “offset downstream” refers to adownstream side of the step flow growth in the SiC substrate.

The bar-shaped stacking fault looks like a trapezoidal shape whose upperbase is the offset upstream when the SiC epitaxial wafer after stackingthe epitaxial layer on a SiC substrate is seen in a plan view. This isbecause the bar-shaped stacking fault in the SiC substrate istransferred to the epitaxial layer and expands to the offset downstreamside. A white line extending in the offset direction within thebar-shaped stacking fault in FIG. 3 is considered to be a basal planedislocation. The bar-shaped stacking fault is a stacking fault which isformed in the SiC ingot and included in the SiC substrate which istransferred to the epitaxial layer. The bar-shaped stacking fault isdifferent from a stacking fault caused by a line defect such as adislocation in a defect image in a photoluminescence image. In theepitaxial layer, the former defect image is trapezoidal, while thelatter defect image is triangular because a starting point is a linedefect.

As shown in FIGS. 2A and 2B, the bar-shaped stacking fault is difficultto identify in the SiC substrate before stacking the epitaxial layerthereon. In addition, as shown in FIG. 3, in the bar-shaped stackingfault in the SiC epitaxial wafer after stacking the epitaxial layer,unlike a stacking fault caused by a dislocation, the contrast of whitelines (basal plane dislocations) within the defect is strong, and thusthe accuracy of classification of a stacking fault is lowered.

Consequently, in the SiC substrate evaluation step according to thepresent embodiment, a bar-shaped stacking fault is observed byirradiating the first surface of the SiC substrate before stacking theepitaxial film with excitation light and extracting light having awavelength range from equal to or greater than 405 nm to equal to orless than 445 nm among photoluminescence light beams emitted from thefirst surface.

FIGS. 4A and 4B are photoluminescence images of the first surface of theSiC substrate. FIGS. 4A and 4B are images obtained by irradiating thefirst surface of the SiC substrate with excitation light using a bandpass filter passing a wavelength of 313 nm and measuring aphotoluminescence image in which light in the vicinity of 425 nm isextracted from photoluminescence light emitted from the first surface.FIG. 4A and FIG. 4B show measurement results obtained at the samepositions as in FIG. 2A and FIG. 2B, and FIGS. 4A and 4B are differentfrom FIGS. 2A and 2B in that light having a wavelength to be observed isnear-infrared light or light in a wavelength range in the vicinity of425 nm.

As shown in FIG. 1, in the photoluminescence spectrum of the SiCepitaxial wafer, a wavelength range in the vicinity of 420 nm is aportion corresponding to the foot of a light emission peak in thevicinity of 390 nm. The wavelength range in the vicinity of 420 nm is awavelength range which is difficult to select also in evaluation of theSiC substrate when conditions of photoluminescence measurement in theSiC epitaxial wafer are followed. On the other hand, in thephotoluminescence spectrum of the SiC substrate, a light emissionintensity in a background other than 390 nm is high, and an intensity ofthe light emission peak in the vicinity of 390 nm is relatively reduced.For this reason, in the evaluation of the SiC substrate, a wavelengthrange in the vicinity of 420 nm can be used.

As shown in FIGS. 4A and 4B, when light in a wavelength range in thevicinity of 425 nm is extracted, a bar-shaped stacking fault looks whitewith respect to a normal crystal portion having no defects. A S/N of abar-shaped stacking fault when measured in this wavelength range isequal to or greater than 4.5, and thus it is possible to more clearlyidentify a bar-shaped stacking fault than in a case of S/N=3.8 when abar-shaped stacking fault is measured in a near-infrared wavelengthrange equal to or greater than 660 nm. In addition, even if themeasurement conditions of the bar-shaped stacking faults are the same,it does not mean that the bar-shaped stacking faults look different (seeFIGS. 2A and 2B).

Therefore, according to the SiC substrate evaluation method of thepresent embodiment, it is possible to identify a bar-shaped stackingfault which is a killer defect of a device at the time of a SiCsubstrate before stacking an epitaxial layer thereon.

A method of extracting light having a wavelength range from equal to orgreater than 405 nm to equal to or less than 445 nm amongphotoluminescence light beams emitted from a first surface of a SiCsubstrate is not be particularly limited, and for example, a band passfilter can be used. A band pass filter having a specific wavelengthtransmits light having a wavelength range of a specific wavelength ofapproximately ±20 nm. For example, when a band pass filter having aspecific wavelength of 425 nm is used, light having a wavelength bandfrom equal to or greater than 405 nm to equal to or less than 445 nm canbe extracted.

For example, a mercury lamp can be used as a light source of excitationlight. An irradiation time of excitation light is preferably equal to orgreater than 1 msec and equal to or less than 10 sec, and is morepreferably equal to or greater than 10 msec and equal to or less than 1sec. When excitation light is sufficiently emitted, the contrast betweenBPD and the other regions becomes clear, while “burning” occurs due tothe excitation light, which also causes a decrease in detectionsensitivity. For this reason, it is preferable to reduce the intensityof excitation light to be emitted. Specifically, the intensity ispreferably equal to or less than 1 W/cm² and is more preferably equal toor less than 500 mW/cm². A wavelength of excitation light to be emittedis preferably equal to or greater than 200 nm and equal to or less than390 nm. The intensity of excitation light to be emitted can be reducedby using a mercury lamp.

Subsequently, it is determined whether to stack an epitaxial layer onthe first surface of the SiC substrate on the basis of results of theabove-described SiC substrate evaluation step (SiC substratedetermination step).

For example, in a case where an area occupied by a bar-shaped stackingfault in the SiC substrate is equal to or greater than ¼ of the surfacearea of the SiC substrate, an epitaxial layer is not stacked. Thebar-shaped stacking fault on the first surface of the SiC substrate istransferred to the epitaxial layer and expands. This is because an areaoccupied by the bar-shaped stacking fault is equal to or greater than ¼in a SiC epitaxial wafer after stacking an epitaxial layer in a casewhere the area occupied by the bar-shaped stacking fault is equal to orgreater than ¼ of the surface area of the SiC substrate at the time ofthe SiC substrate.

In addition, for example, the determination may be performed on thebasis of the number, density, length and the like of the bar-shapedstacking fault. For example, in a case where equal to or greater than 10pieces/cm² of bar-shaped stacking faults are confirmed in the SiCsubstrate, an epitaxial layer is not stacked. In addition, for example,in a case where a bar-shaped stacking fault of ½ or more of the diameterof the wafer is confirmed in the SiC substrate, an epitaxial layer isnot stacked.

The determination step may include a second determination step ofdetermining a film thickness of an epitaxial layer to be stacked, inaddition to a first determination step of determining whether to stackan epitaxial layer. As described above, a bar-shaped stacking fault onthe first surface of the SiC substrate is transferred to the epitaxiallayer and expands. As the film thickness of the epitaxial layerincreases, the bar-shaped stacking fault expands more, and thebar-shaped stacking fault confirmed on the surface of the epitaxiallayer becomes larger.

A relationship between the degree of expansion of a bar-shaped stackingfault and the thickness of an epitaxial layer may be obtained on thebasis of a calibration curve based on actual measurement or may becalculated from an offset angle of a SiC substrate.

Finally, an epitaxial layer is stacked on the first surface on the basisof results of the determination step (SiC substrate stacking step).

By performing the determination step, for example, it is possible toobtain a SiC epitaxial wafer including a SiC substrate and an epitaxiallayer stacked on a first surface of the SiC substrate, in which an areaoccupied by a bar-shaped stacking fault is equal to or less than ¼ of anarea of the epitaxial layer. In addition, for example, it is alsopossible to obtain a SiC epitaxial wafer having no bar-shaped stackingfault.

While preferred embodiments of the invention have been described andillustrated above, it should be understood that these are exemplary ofthe invention and are not to be considered as limiting. Additions,omissions, substitutions, and other modifications can be made withoutdeparting from the spirit or scope of the present invention.Accordingly, the invention is not to be considered as being limited bythe foregoing description, and is only limited by the scope of theappended claims.

What is claimed is:
 1. A SiC substrate evaluation method, comprising:observing a bar-shaped stacking fault by irradiating a first surface ofa SiC substrate before stacking an epitaxial layer with excitation lightand extracting light having a wavelength range of equal to or greaterthan 405 nm and equal to or less than 445 nm among photoluminescencelight beams emitted from the first surface, wherein the first surface ofthe SiC substrate has an offset angle from a {0001} plane, anirradiation time of the excitation light is equal to or greater than 1msec and equal to or less than 10 sec, and an intensity of theexcitation light is equal to or less than 1 W/cm², and wherein thebar-shaped stacking fault extends in a bar shape in a directionsubstantially perpendicular to the offset direction, the bar-shapedstacking fault has a length in a direction substantially perpendicularto the offset direction with respect to a width in the offset directionis long and the bar-shaped stacking fault has an aspect ratio(length/width) is equal to or greater than 2, and wherein the offsetdirection is the direction of a vector obtained by projecting a normalvector of a {0001} plane onto the first surface of the SiC substrate. 2.The SiC substrate evaluation method, according to claim 1, wherein awavelength of the excitation light is equal to or greater than 200 nmand equal to or less than 390 nm.
 3. The SiC substrate evaluationmethod, according to claim 1, wherein the bar-shaped stacking fault is asingle Shockley-type stacking fault extending in a bar shape in adirection substantially perpendicular to an offset direction.
 4. Amethod for manufacturing a SiC substrate, comprising: an evaluation stepof evaluating the first surface of the SiC substrate using the SiCsubstrate evaluation method according to claim 1; a determination stepof determining whether to stack an epitaxial layer on the basis ofresults of the evaluation step; and a growing step of growing anepitaxial layer on the first surface on the basis of results of thedetermination step.